PURPOSE: A semiconductor device is provided to make a semiconductor device thin by making a resin sealing member thin, and to improve an electrical characteristic by greatly reducing the floating capacitance of a lead. CONSTITUTION: A resin sealing member(12) is prepared. The first semiconductor chip has the first and second outer terminals on a circuit formation surface. The second semiconductor chip has the third and fourth outer terminals on a circuit formation surface. The first, second and third leads extend to the inside and outside of the resin sealing member. The first lead is ramified into two in at least the resin sealing member. One of the ramified first lead is fixed to the circuit formation surface of the first semiconductor chip. The other of the ramified first lead is fixed to the circuit formation surface of the second semiconductor chip. The second lead is fixed to the circuit formation surface of the first semiconductor chip, connected to the second outer terminal. The third lead is fixed to the circuit formation surface of the second semiconductor chip, connected to the fourth outer terminal. The first and second semiconductor chips are operated by a clock signal supplied to the first lead while the back surfaces of the chips face each other. The first and second chip control signals are input from the outside of the resin sealing member to the second and third leads to make the first and second semiconductor chips be in a low power consumption mode, respectively.